author(s)
Naga Satyasri CH, Madhumathi T and Sairam Kumar DV

abstract
A laboratory experiment was carried out in the Department of Entomology to know the toxic effect of synergists on commonly used insecticides against Tribolium castaneum Herbst. The synergists such as PBO, DEF and TPP showed synergistic factors of 89.58, 238.80 and 153.57 at LC₅₀ and 3.17, 6.0 and 503 at LC_99.9 level respectively with malathion. The corresponding synergistic values for dichlorvos were 58.8, 35.33 and 15.14 at LC₅₀ and 2.50, 2.13 and 0.32 at LC_99.9 level, while these values were 56.42, 25.48 and 21.03 at LC₅₀ level and 1.80, 0.6 and 0.49 at LC_99.9 level for deltamethrin. The levels of resistance to malathion, dichlorvos and deltamethrin are brought down significantly with all the three synergists viz., PBO, DEF and TPP.